In a heat exchanger in an ordinary household or commercial air conditioning system, as shown in FIG. 1, there are inlet/outlet tubes 1 and 2; headers 3 at two ends are responsible for distributing and collecting a refrigerant; flat tubes 4, with small channels in the interior thereof, are inserted into the headers 3 by means of slots in the headers 3, and are responsible for heat transfer between a refrigerant and air when the refrigerant is circulating. Corrugated fins 5 between the flat tubes are responsible for enhancing the heat exchange effect. When air, driven by a blower, flows past the fins 5 and flat tubes 4, the temperature difference between the air and refrigerant causes heat to be transferred between these two media. In the case of condenser applications, once air is flowing it absorbs heat and flows out; in the case of evaporator applications, once air is flowing it dissipates heat and flows out.
In the case of evaporator and heat pump applications, since these involve the problem of the formation and melting of frost as well as condensed water, the heat exchanger will be positioned so that the headers are arranged in a horizontal direction, while the flat tubes are arranged in a vertical direction, to facilitate the drainage of water. In order to balance the flow rates of refrigerant in each of the flat tubes, a pipeline is added in the header, with different slots being formed on the pipeline according to actual circumstances in order to obtain a better heat exchange effect.
To obtain a better heat exchange area, two heat exchangers may be used (as shown in FIG. 2). In some confined-space applications, such as regenerator applications, and applications in which a motor vehicle air conditioning heat exchanger and a water tank are in parallel, etc., two or more heat exchangers will also be used.
In the case of these conventional heat exchangers, the refrigerant-side temperature will change as refrigerant flows in the flow direction and undergoes heat exchange, while the temperature of inlet air is steady; this will lead to imbalance in the heat exchange efficiency. In the case of through-flow blower applications in particular, such a temperature difference will lead to severe non-uniformity in the temperature of outgoing air, so that the user experiences a significantly reduced level of comfort during use.
To obtain a balanced outgoing air temperature, the design will often employ two heat exchangers. Referring to FIGS. 3 and 4, one of the two heat exchangers is an inlet heat exchanger, while the other is an outlet heat exchanger. Once air has flowed through the two heat exchangers, the air temperatures have been mixed, so a better outgoing air temperature is obtained.
Referring to FIGS. 5-6, in the case of an indoor machine application using twin through-flow blowers 7 in particular: since the temperature difference between top and bottom parts of the air conditioning air outlet of the single heat exchanger (as shown in FIG. 5) is large, the level of comfort will be reduced; therefore, two heat exchangers will often be used (as shown in FIG. 6). Although a more uniform outgoing air temperature can be obtained, the cost of two heat exchangers is high, and the level of processing difficulty is high; moreover, the provision of connecting tubes 8 at the joint between headers will reduce the heat exchange area.
In view of the above, there is definitely a need to provide a novel heat exchanger that is capable of at least partially solving the abovementioned problems.